A dual pinion type rack bar is a type of a rack bar for use in a steering apparatus of a vehicle, such as an automobile, having toothed portions at two locations, each toothed portion having a plurality of rack teeth. One of the toothed portions is engaged with a steering pinion of a steering shaft of a vehicle, and the other toothed portion is engaged with an assist pinion of an assisting mechanism. Some dual pinion type rack bars are designed such that the toothed portions at the two locations have an angular difference around the axis, depending on a positional relationship between the steering shaft and the assisting mechanism of the vehicle.
JP2014-124767A discloses a method for manufacturing a dual pinion type rack bar in which a first bar member having a toothed portion and a second bar member arranged coaxially with the first bar member are friction-welded by being rotated relative to each other around the center axis and then another toothed portion is formed on the second bar member by cutting. By forming the toothed portion on the second bar member after joining the first bar member and the second bar member to each other, the accuracy of the angular difference between the toothed portion of the first bar member and the toothed portion of the second bar member is improved.
In this method for manufacturing the rack bar, when there is a misalignment or inclination of the second bar member with respect to the first bar member to which the second bar member has been joined, the straightness of the rack bar is degraded.